Neon lights are widely used in commercial applications as decorative enhancements and back lights. For example, they are used to highlight architectural features or to display names, logos and the like.
Neon lights are generally chosen for their neon effect or glare which demands the viewer's attention. This ability to draw attention outweighs the many drawbacks associated with neon lights. They are fragile, high voltage, energy consuming, monochromatic devices with inconsistent life patterns. They are labour intensive and require licensed tradesmen for installation and replacement. From a practical standpoint, any other type of lighting would be desirable if it could produce the attention demanding impact associated with neon.
There are several prior art references that disclose the use of light emitting devices as illuminators in a strip like illumination device. For example, U.S. Pat. Nos. 6,472,823, 6,371,637, 6,283,612, 5,343,375 and 5,321,593 describe strip type lighting devices which incorporate light emitting devices as the illumination source.
For example, U.S. Pat. No. 6,158,882 discloses a LED lighting apparatus in an elongated format used for illuminating vehicle interiors. The lighting apparatus comprises a light tube with an interior space and has a plurality of light emitting devices and current limiting resistors contained within the interior space of the light tube. The illumination intensity of the light emitting devices is controlled by a dimming module in electrical contact with the LEDs and electrically connected to the vehicle source of power.
In particular, U.S. Pat. No. 6,361,186 discloses a simulated neon lighting device which is created using light emitting devices as the light source. In this device an elongated, translucent diffuser of circular cross-section is mated with an elongated opaque tubular housing of constant cross-section with a lengthwise slot. The diffuser is held in longitudinally aligned abutment against the edges of the housing slot to form a chamber between the housing and the diffuser and light may only be emitted through the diffuser. A plurality of light emitting devices is aligned in a linear array in the chamber and the reflection and refraction of light by the tubular diffuser produces a neon-like glow or glare along the exposed surface of the diffuser. It was stated that this provides a durable, low voltage, low energy, non-gaseous, inexpensive, easy to install, easy to maintain, chromatically versatile, long life fixture which looks like neon light.
In addition, Lumileds Lighting, LLC provided a chipstrip contour lighting product that comprised of a linear array of solid-state light emitting devices mounted on an elongated printed circuit board. These circuit boards were encased inside a translucent polycarbonate housing, which was subsequently sealed at both ends. The unit included interconnects at each end in order to allow for the ease of connectivity of adjacent units. Ideally, a series of these units could be mounted end to end in order to produce a continuous contour of light. However, having regard to this mounting scenario, if there are thermal temperature gradients in the environment of use, the ends of adjacent units would have to be separated when fixedly mounted to a surface, in order to enable thermal expansion and contraction. FIG. 1 illustrates a typical end to end setup of adjacent housings 1 having inserted therein a printed circuit board 2 with LEDs 3 thereon. As identified, a separation region 4 between the housings is provided in order to account for thermal expansion due to temperature variations. This type of placement of adjacent housings however, produces dark spots within the separation region and therefore a continuous contour of light may not be perceived.
While there are many devices that incorporate light emitting devices integrated into an elongated lighting device in order to form a continuous light contour, the use of these devices is intended to be at fairly stable temperatures. However, upon the placement of these types of devices in an environment in which there will be thermal gradients, the nature of these devices through the incorporation of a plurality of different materials and therefore varying thermal expansion coefficients, in addition to the potential end to end placement thereof, can result in potential problems. These problems can include leakage and breakage of the units due to differential expansion of the various components, in addition to a discontinuous light contour being created if thermal expansion is not accounted for in the placement of the devices. Therefore there is a need for an new lighting system that enables the creation of a continuous contour of light in environments having thermal gradients.
This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.